Tonight, nascar fans are taking sides in a big debate. What should happen when a race car driver retaliates against another car on the track? And not just any driver. The renowned, respected jeff gordon, called the wonder boy. Tonight, he was given a big fine, but he says he had been taunted and taunted and was compelled to act. Abc's david wright. And mayhem in the late laps. Reporter: An intentional accident at more than 100 miles an hour. A move so controversial it all ended up in a brawl. Somewhere in the middle of all that is jeff door gone. Reporter: Take a look again. Watch the number 24 car, jeff gordon, slowing down, and deliberately pushing the number 15 car, driven by clint bowyer, into the wall, wrecking bowyer's car and his chances. Other drivers are outraged. The retaliation is out of control in this sport and it's going to get somebody hurt. Reporter: Fans are debating on twitter. Respect for jeff gordon? That doesn't exist anymore, said one. Another said, jeff, we're behind you 100%. For these two drivers, a bitter end to a season-long feud. Run into me numerous times. I had it. It's pretty embarrassing for a four-time champion. Jeff gordon! Reporter: The man at the center of this incident is one of the sport's most popular stars. The only nascar driver ever to host "saturday night live." Every time I get in a car, there's a chance could crash and burn in front of millions of people. I guess I am prepared for this show. Reporter: Jeff gordon has even guest starred on "sesame street." Not the guy you'd expect to be outsetling scores. In gnat car, they have a phrase for this. "Have at it, boys." When cars are whipping around these tracks at more than 200 miles an hour, it can be a most dangerous game. This is kind of a new nascar, where they've told the drivers to have at it and you settle things among yourselves. Reporter: So, what's next for gordon? Late today, nascar fined him $100,000. David wright, abc news, los

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